When you are multiplying numbers that are written in scientific notation, you can use this formula:
(n x 10a) • (m x 10b) = (n · m) x 10a+b
This means that you multiply the numbers in front of the 10 and then add the exponents.
So you have this problem and we can follow the formula above.
(7 * 10^3) * (8 * 10^-9)
(7 * 8) * 10 ^ 3 - 9
56 * 10^-6
The last step will be to make sure the answer is in proper scientific notation. This means that there is one digit followed by a decimal place. So for this problem the decimal place must be moved one place to the left, and the exponent reduced by 1.
5.6 * 10^-5
If you have any questions about this please let me know.